A light emitting diode (LED) with transparent doping layer (TDL) is fabricated. The I-V characteristics and the electroluminescence intensity of a LED with TDL significantly increase more than that of a LED without TDL. The improvement of optical and electrical properties is attributed to the excellent carrier injection through the n-ZnO layer into Si quantum dots embedded in silicon nitride film ...
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A denial-of-service (DoS) attack which can waste wireless resources by using the destination address of IP packets is introduced. To prevent the attack more effectively, early detection, efficiency, and small overhead are suggested as requirements in a detection system. We use a second order Markov model to suggest a detection system against the attack in 3G1x system. The states in the model are r...
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A novel technique is introduced to graphically analyze the runtime behavior of block replacement algorithms used in cache controllers. The new method allows a behavioral comparison of two or more algorithms, previously impossible due to the vast amount of data involved in cache simulations. Absolute and relative comparisons are demonstrated and the application in the development of a modified LRU ...
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Specific features of room-temperature I-V and C-V curves of Al/Si1-xGex/n-Si/Al structures with x = 0.1 - 0.3 and different crystalline orientations of the Si1-xGex layers are studied experimentally and attributed to influence of quantum confinement effect.
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Currently, denial-of-service (DoS) attacks remain among the most critical threats on the Internet. Ironically, although a major objective of Internet protocol design was to prevent DoS attacks and to maintain network connections in order to provide essential services to the masses uninterruptedly, the Internet is suffering significantly from distributed DoS (DDoS) attacks at present. In recent yea...
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Maximal ratio transmission (MRT) is designed assuming the availability of perfect channel state information (CSI) at both the transmitter and the receiver. However, perfect CSI is not available in practice. This paper investigates the impact of Gaussian estimation errors on the MRT performance in independently and identically distributed (i.i.d.) Rayleigh fading channels. We derive the cumulative ...
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We study the performance of multiuser selection diversity based on absolute signal-to-noise ratio (SNR)-based scheduling and normalized SNR-base scheduling. Our performance criteria include system capacity as well as access probability, average access time, and average access rate of individual users. Closed-form expressions are obtained for these performance measures when the users are subject to...
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The identities of two circular functions are used, through a geometric construction onto a unit circle representing the z-domain of discrete systems, to generate a set of planar triangles from which both edge length and area can be used to build and model a 3D data structure of the system.
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Many multimedia services of the next generation mobile telecommunication systems have an asymmetric traffic distribution between uplink and downlink. The combination of the time division duplexing (TDD) with the time division multiple access (TDMA) technique in the Universal Mobile Telecommunications System (UMTS) allows an asymmetric use of radio resources due to the flexible allocation of time s...
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Syntactic and semantic analysis are established topics in the area of compiler construction. Their application to the understanding and restructuring of large software systems reveals, however that they have various shortcomings that need to be addressed. In this paper we study these shortcomings and propose several solutions. First, grammar recovery and grammar composition are discussed as well a...
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Component based software engineering is a good response to actual systems needs: flexibility and adaptability. In this context, design techniques based on software composition and verification techniques proving that the design properties are well implemented, are current and actively studied problematics. We present a composition design technique based on a formally defined theory: the whole-part...
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We report high refractive-index contrast microring resonators laterally coupled with waveguide crossings as add-drop filters in silicon nitride. We demonstrate tuning of filter characteristics by simultaneously varying the widths of waveguide crossing and microring.
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Synchronization is critical in the design of an OFDM receiver. Large timing offsets result in a loss of orthogonality between subcarriers, ISI, and severe bit error degradation. To minimize this degradation, standards incorporate preambles intended for all OFDM acquisition functions including automatic gain control (AGC) and synchronization. Several synchronization algorithms have been proposed. U...
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In present paper, different aspects of a solar powered TPV system are under theoretical and experimental study, such as heating the emitter of photons by focusing sunlight, returning the sub-bandgap photons by reflecting IR radiation from cell back surface, and estimating the cell conversion efficiency being guided by semiempirical approaches. Efficiency of 25% can be obtained in GaSb cells withou...
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Estimations of spatio-diversity gain (SDIV) in the wideband directional channel suffer from imprecise modeling of multipath angular spread (AS). Using previously published measurements and a synthetic array and channel parameterization, we show that AS exhibits dependence on both line-source distribution and operating frequency. As a result, SDIV is calculated through the integration of a continuo...
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In wireless data communications, it has been realized that by adapting the transmit power and rate, not only to the channel conditions, but also to higher layer parameters, such as the buffer occupancy and data arrival statistics, the system performance can be significantly improved. However, most of the existing approaches deal only with single user scenarios. In this paper, we consider a multius...
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A position sensorless control approach for IPMSM proposed in this paper is specifically developed for air conditioning compressor drives in hybrid electric vehicles. For stable sensorless operation, it makes the best use of two beneficial aspects appearing in the motor under the sinusoidal PWM voltage drive without any current minor loops. Unlike traditional sensorless approaches being on the basi...
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In this paper, we propose a fuzzy kernel C-means clustering algorithm (FKCM) which is based on conventional fuzzy C-means clustering algorithm (FCM). This new FKCM algorithm integrates FCM with Mercer kernel function and deals with some issues in fuzzy clustering. The properties of the new algorithms are illustrated the FKCM algorithm is not only suitable for clusters with the spherical shape, but...
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Recent experiments around the world., exemplified by those carried out at the LUNA (Laboratory for Underground Nuclear Astrophysics) collaboration, have shown that an anonymously high electron screening effect on nuclear fusion rate occurs during accelerator-driven low energy (e < 100 (where E ...
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In this paper, we present a methodology for combining acoustic-phonetic knowledge with statistical learning for automatic segmentation and classification of continuous speech. At present we focus on the recognition of broad classes-vowel, stop, fricative, sonorant consonant and silence. Judicious use is made of 13 knowledge-based acoustic parameters (APs) and support vector machines (SVMs). It has...
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The problem of allocating radio resources in the downlink of a CDMA network is studied. In Kwan et al. (2004) the modulation and coding schemes, numbers of multicodes and transmit powers for all mobile stations (MS) are jointly chosen so as to maximize the total allocated bit rate taking into account MS traffic loads. This approach leads to a mixed integer non-linear programming (MINLP) problem wh...
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This paper presents new results with a permutation-based genetic algorithm (GA) to predict the secondary structure of RNA molecules. More specifically, the proposed algorithm predicts which canonical base pairs forms hydrogen bonds and builds helices, also known as stems. We discuss a GA where a permutation is used to encode the secondary structure of RNA molecules. We have tested RNA sequences of...
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We compare existing component technologies for embedded systems with respect to industrial requirements. The requirements are collected from the vehicular industry, but our findings are applicable to similar industries developing resource constrained safety critical embedded distributed real-time computer systems. One of our conclusions is that none of the studied technologies is a perfect match f...
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